Aptamer-functionalized Near-infrared Quantum Dots Combined with Flow Cytometry for Rapid Detection of Leukemia Cells

As a haematological malignancy,leukemia poses a great threat to human health and life. Its early and rapid diagnosis is crucial for the improvement of the cure and survival rate of patients. In this paper,a novel leukemia cell assay strategy has been proposed based on aptamer-functionalized quantum dots( QDs)combined with flow cytometry. In this strategy,a biotin-labeled cancer-specific aptamer was adopted as the recognition molecule,and avidin-modified QDs with near-infrared fluorescence emission were utilized as the signal generator. Through the biotin-avidininteraction,QDs could be functionalized with aptamers to construct a novel aptamer-QDs fluorescent nano-probe. This probe could specifically bind to target cell surface via the interaction between aptamers and receptors on cell membrane,thus indicating the presence of the target after analysis with a flow cytometer. As proof of concept,the detection of human acute lymphoblastic leukemia CCRF-CEM cells was performed using the specific aptamer,Sgc8 c,as a demonstration. Results showed that the modification with Sgc8 c did not markedly influence the fluorescence emission and size of QDs. With a simple incubation with cell samples for just 30 min,this Sgc8c-QDs nano-probe could successfully achieve the highly selective detection of CCRF-CEM cancer cells both in buffer and in serum. By comparison with the traditional fluorescent dye labeling method,this Sgc8c-QDs-based strategy exhibited a substantial enhancement in analysis sensitivity for CCRF-CEM cells in buffer,which realized about 4. 3 folds signal-to-background ratio of the FAM-labeled Sgc8c( FAM-Sgc8c) strategy. In particular,when used for serum sample analysis,the Sgc8c-QDs nano-probe still reserved a perfect applicability and displayed a relatively high signal-to-background ratio of about 9,while FAM-Sgc8 c nearly lost the detection efficiency at the same concentration. It has been clearly verified that this aptamer-QDs strategy is facile,fast,washing-free,specific and sensitive,which might hold a great potential as a versatile technique for diagnosis and prognosis applications in cancer researches.